Well I'm not really cooking on gas but my Range Rover is running on Gas (LPG). It has taken me about 4 days in time, which has been spread over a few weeks doing it when I could, when it was not raining. But I have now finished the job apart from a few bits of tidying up and tweaking, the car switches over seamlessly from petrol to gas.
Here is a pic under the bonnet for those that are not used to looking under bonnets the yellow things are the gas injectors, the round silver thing in the bottom left of the pic is the LPG vaporisor.